What is the discovery of penicillin?

The discovery of penicillin refers to Alexander Fleming's discovery of a mould that could kill staphylococcus bacteria.

How was penicillin discovered by Alexander Fleming?

Penicillin was discovered by mistake by Alexander Fleming as a spore found its way onto a staphylococcus petri dish whilst he was away on holiday.

Who really discovered penicillin?

Scottish biologist Alexander Fleming.

When was penicillin first used?

Penicillin was first used on a human in the 1930s by Howard Florey and Ernst Chain.

Who discovered penicillin before Fleming?

Nobody discovered penicillin before Alexander Fleming; he discovered the new antibiotic in 1928 and published his findings - allowing other scientists to expand on his study.

Discovery of Penicillin: History & Fleming

Discovery of Penicillin

The discovery of penicillin was a huge moment, not only for people who could now treat their bacterial illnesses but also for the pharmaceutical industry which is worth between £200 and £300 billion today. Alexander Fleming found the world's first antibiotic in 1928 thanks to the urgency that war provides and the lucky contamination of a petri dish.

Get started

Antibiotic

A type of medicine that inhibits the growth of bacteria.

Penicillin

A group of antibiotics used to treat infections caused by a range of bacteria.

However, it wasn't until World War II that it was widely used. Let's go on a journey to find out exactly how this happened!

Alexander Fleming penicillin discovery

With the understanding of germs emerging in the second half of the nineteenth century, Louis Pasteur and Robert Koch laid down the foundations for Alexander Fleming's discovery of penicillin. Their understanding of how microbes caused specific diseases was key to his success, but Fleming's breakthrough actually happened through sheer luck. Now let's examine a timeline of the long story of penicillin from identification to mass consumption!

Date	Event
1861	Louis Pasteur's Germ Theory allowed scientists to understand bacteria.
1876	Robert Koch found and isolated the bacteria that causes anthrax. He went on to do this for many other diseases.
1914-18	Infection from many septic wounds caused lots of deaths in World War I. See Medicine on the Western Front for more details. These were caused by staphylococci bacteria.
1921	Alexander Fleming saw that an ingredient found in tears, lysozyme was able to stop the progress of some germs as an antiseptic, but not all of them!
1928	Fleming found mould from another room in his laboratory growing on a petri dish with staphylococci bacteria on it. Around this mould, no more bacteria grew. Penicillin fungi had killed the bacteria.
1929	Fleming thought that this was another antiseptic, which helped slow infection but did not kill bacteria because he did not inject it into any patients. He published his findings but dismissed their importance.
1940	As World War II started in 1939, there was a huge demand for effective treatment for soldiers whose wounds were infected. Howard Florey and Ernst Chain tested penicillin on eight mice and then managed to produce enough penicillin by their freeze-drying method to inject it into an infected patient. This was successful and it became the first antibiotic that killed bacterial microbes.
1941	The US government commissioned several companies to produce penicillin on a grand scale. These included pharmaceutical giants like Pfizer and Merck.
1945	World War II ended and penicillin treated around 250,000 British and United States soldiers. After the war, production increased and became cheaper. This, coupled with the introduction of the National Health Service (NHS), led to mass consumption of this antibiotic from the general population.

Did you know? Alexander Fleming was a Scottish physician who developed a keen interest in antiseptics. Originally serving in the Territorial Army until 1914, he had been trying to understand the interactions between blood and bacteria since World War I. More than ten years later, he was studying the flu virus and saw some mould that even after immense dilution would kill staphylococcus bacteria. This was penicillin.

Discovery of Penicillin Alexander Fleming StudySmarter Fig. 1 - Alexander Fleming

Penicillin mould is as temperamental as an opera singer.

- John L. Smith, Pfizer Manufacturing Supervisor

Why was penicillin so difficult to store and reproduce?

Well, as naturally occurring fungi, the conditions in which it was kept needed to be carefully monitored. The process was as difficult as John L. Smith describes above:

Use a clean culture of the mould.
Ferment the mould in giant containers, this was named "Deep Tank Fermentation".
Extract and purify the mould before putting it in bottles, being careful to avoid cross-contamination.
Dehydrate the drug using a freeze-drying method.

The cycle took place in this manner during World War Two, but afterwards, Pfizer added a further crystallisation stage to increase longevity and purity.

Facts about penicillin

Let's look at some key facts about penicillin.

Penicillin works by stimulating enzymes to destroy the cell walls of bacteria.
The first use of penicillin on a citizen was on Anne Miller in 1942, who became infected after she had a miscarriage. Penicillin saved her life.
Fleming won the Nobel Prize in 1945 for his discovery and in his acceptance speech gave a warning that bacteria could become resistant to it.
1% of the population is allergic to penicillin. It can even result in an anaphylactic shock in some cases, threatening the life of the person who took it.

Anaphylactic shock

A rare but extreme reaction to something a person is allergic to, which can be life-threatening.

Uses of penicillin

The National Health Service (NHS) website states that penicillin is effective against bacterial infections, but not viral ones like flu. It is often used against bacteria that can be contagious such as pneumonia or sexually-transmitted chlamydia.

Sometimes doctors might use penicillin during operations where the risk of infection is high.

Nowadays, the use of penicillin is less common. This is due to the increased presence of viruses and, just as Fleming feared, the fact that some bacteria or "superbugs" display resistance to this antibiotic. When used against mild bacteria, it may therefore be less potent than when treating serious infections.

Effects and Facts Penicillin

Most medicines come with a series of side effects that need consideration before using them and penicillin is no different. The NHS declare that these normally affect the digestive system and often involve nausea or vomiting.

Antihistamines, which are often used against hay fever, are effective in treating more severe reactions like coughing or a rash. Drug interactions also need consideration when taking penicillin. For example, methotrexate, a drug that fights arthritis, interacts negatively with penicillin.

Types of penicillin

As time has progressed, different variations of penicillin have combated different medical challenges. It is easy to split them into four separate groups.

Discovery of Penicillin Penicillin chemical structure StudySmarter Fig. 2 - Penicillin chemical structure

To understand them fully let's first examine a couple of terms.

Gram-positive bacteria

Bacteria with a thick cell wall

Gram-negative bacteria

Bacteria with a thin cell wall; normally more resistant to antibiotics

Naturally-occurring penicillin

The penicillin that Alexander Fleming found and pioneered is known as Penicillin G. Another variation of this is Penicillin V which can be digested, rather than injected. These focused on attacking gram-positive bacteria.

Semi-synthetic penicillin

These semi-artificial penicillins such as Ampicillin are often effective against both gram-positive and gram-negative bacteria.

Penicillin with a Beta-Lactamase inhibitor

Penicillins that have a beta-lactamase inhibitor block chemical reactions in the body. This allows the drug to work more effectively. These include Amoxicillin.

Antipseudomonal penicillin

Often used for urine infections, these types of penicillins, e.g. Piperacillin, are best at fighting against gram-negative bacteria that is particularly difficult to tackle.

Importance of penicillin

As evidenced by Fleming's Nobel Prize in 1945, the discovery of penicillin was of great importance to the medical and wider community.

In World War II, it was instrumental in the quick recovery of soldiers who had bacterial infections; it saved the lives of 15% of British and American soldiers whose wounds would have previously been fatal. These men could often return to the battlefield.

Penicillin also acted as the father of many other antibiotics, not just penicillin variations, for instance, Miyomycin (1956)- a form of chemotherapy to fight cancer.

Did you know? It is interesting to note that chemical use against cancer also originated on World War II battlefields as scientists analysed certain properties of the chemicals found in mustard gas.

Crucially, penicillin is an antibiotic that kills germs and not an antiseptic that simply helps to prevent them. For this reason, it is still produced by pharmaceutical giants such as Pfizer and used against many bacteria today.

Discovery of Penicillin Pfizer headquarters in New York StudySmarter Fig. 3 - Pfizer headquarters in New York

Discovery of Penicillin - Key takeaways

Scientific knowledge of bacteria and microbes laid the foundations for the discovery and production of penicillin.
Infection in World War I from staphylococci bacteria created the necessity for an antibiotic to prevent soldiers from dying from their wounds.
By chance, Alexander Fleming found some mould growing on a petri dish that killed this bacteria, this became known as penicillin.
Howard Florey and Ernst Chain developed this discovery, finding how to store and mass-produce penicillin and injecting it into a patient.
Penicillin became vital as an antibiotic in World War II. Around 250,000 British and American soldiers were treated with it. It was effective, saving around 15% of them from their wounds by killing infectious bacteria. Pharmaceutical companies like Pfizer were vital in this mass-production process.
While still in use today there are many different forms that diversify from Fleming's original penicillin. As he predicted, some bacteria have developed resistance to penicillin.

Discovery of Penicillin

StudySmarter Editorial Team

Alexander Fleming penicillin discovery

Facts about penicillin